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Old Feb 22, 2004, 2:57 PM   #11
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My own pragmatic view:

Why muddy up the picture by pitching one frirmware vs another? After all unlike the F717 previously, the F828 can put out a RAW picture, which can be used by newly available common processors like Photoshop. Wouldn't this approach narrow the scope back to just lens/CCD, and put all cameras analysis back on an even keel?
--> comparing a RAW from the A2 vs a RAW output form the F828 with the same software... may be the differences lay in the extra color type of CCD, the RGB CCD, or may be its complementary colored one, all 3 made by Sony... or maybe it's all in the lens after all...
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Old Feb 22, 2004, 3:03 PM   #12
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Not necessarily because of the filtering process (Real Color) which is involved during acquisition. It's like trying to "undo" the antialiasing filters which are bonded to the sensor. Any effects are going to be there whether or not one uses RAW or processed data.

With the F828 it is easy to see that some of the aliasing caused by JPG processing is absent from the RAW data, but even RAW data "may" be subject to firmware processing during data acquisition and before saving to media. This is absolutely the case with some of Canon's images and unknown with others.

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Old Feb 22, 2004, 3:38 PM   #13
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1. Isn't the "antialiasing filters which are bonded to the sensor" a common element regardless of which camera its mounted in? If we can agree on this point then if the CA is present in one camera and not in the other can we deduce that it's not coming from the sensor(or its type) then when using RAW, but originating from the lens instead?

2. IMO it's a bummer if any firmware try to modify the integrity of the raw data in anyway (beside packing the bits and appending the camera parameters...) Wouldn't this for all purposes defeat having RAW in the 1st place which some previous Dimage owners have accustomed to since they didn't appreciate the way their camera processed the data?
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Old Feb 22, 2004, 4:01 PM   #14
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With the exception of Kodak Professional Cameras with the Nikon Body which all had removable antialiasing filters, and the Sigma SD9 and SD10 and Kodak 14n which have no antialiasing filter, most digicams do have them. On the other hand, how they affect the image as well as the bayer process itself which differs among digicam manufacturers and its effect on various parts of image quality such as sharpness (edge roll-off pixel count, etc.) and color smear differ from instrument to instrument and this precedes the RAW data as written to media.

It would make it much easier if the term RAW really meant the same thing for each manufacturer, but indeed it does not. Essentially all we can really know without insider information from each manufacturer is that white balance, exposure compensation, sharpness algorithms (and not even this in all cases), contrast, brightness and saturation are generally not tweaked before saving RAW data. Therefore the firmware processing which may or may not be applied (such as Canon's DIGIC) prior to saving the file as RAW is still an unknown entity and negates using RAW files processed by identical algorithms as a means of determining causality for issues such as purple fringe.

In the old days, photographers were astounded by the beauty and lack of barrel distortion with the old Canon Pro 70 at 28mm wide angle. It was compared with the Sony DSC-D700's 28mm which had noticeable barrel distortion at the same focal length. Everyone thought Canon must have simply had a better lens design, but as it turned out they were simply applying firmware correction in firmware prior to saving to the media.

Unfortunately for those of us trying to decipher the purple fringe issues, we can't make assumptions about what is and is not being done in firmware, IR cut filtering, antialiasing and such prior to saving the image. There is simply too much going on that we are not privy to.

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Old Feb 22, 2004, 5:32 PM   #15
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Quote:
Originally Posted by NHL
It's both, one leads to the other: it starts with the optic but is made worse by the electronics... http://www.dpreview.com/learn/?/Glos...rations_01.htm

Chromatic Aberration is not a universal problem: some cameras such as the D7's/A1... has an excellent apochromatic G series zoom which can achieve relatively free CA at all focal lenghts!
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Not sure where I said it, but I honestly was beginning to wonder about this. A lens that gets away with "bad behaviour" on a 35 mm slide ( or a lower-pixel-count sensor??) may habe trouble with the far more critical situation with a highky packed, smaller area of film plane.

I keep hearing "lens"!...."sensor"!... But it does not always happen with digital, and I am _sure_ never happened, as badly as it does here, with 35mm.
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Old Feb 22, 2004, 5:34 PM   #16
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The A1 (5 mpxl CCD sensor) has no purple fringing, but the A2 which uses exactly the same lens, but has a different CCD (8 mpxl) does exhibit purple fringing under some conditions. Photos showing the A2's PF have been posted on another forum.

BTW, the A2 CCD is the same one that is used in the Sony 828. The 828 has severe purple fringing issues.
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Sorry. Have to say it....this still means it _could_ be sensors. IT certaonly seems to have more to do with sensors than lenses, whether because of quality, or Pixels / cm2, I am not sure.
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Old Feb 22, 2004, 5:47 PM   #17
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Just an observation [arguably based on a limited sample size]:

CCDs with 8 Mpixels on a two dimentional 2/3 type array seem to exacerbate PF even with high quality optical systems feeding them with photons. The 5Mpx Sony 717 had negligable PF and the 5mpx DiMGE A1 has no PF. Both have very high quality lenses. PF on the Sony 828 and the DiMAGE A2 is quite evident. Both of these 8 Mpx cameras have high quality lenses--the CCD is the common link.

As Lin has pointed out, there are many factors to consider, however I can't help but think that a common factor in the case of the A2 and the 828 is the lens array on the Super HAD imager, which now has much smaller diameter lenses somehow refracting some part of the optical spectrum [might be outside of the visible range] to produce the PF perhps due to a blooming-like phenomenon.

c.f., http://www.sony.net/Products/SC-HP/s...super_had.html
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Old Dec 18, 2004, 3:15 AM   #18
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The problem with the big deal made about CA (purple fringe) is that it is existant in film cameras but you don't get to see your images on a computer screen or on an LCD screen, like on digital cameras, so you don't know it's there. When the picture is printed, there is no purple fringe.

style="BACKGROUND-COLOR: #000000"People are spoiled now with digital cameras, they see the image right away so they pick at everything and they forget what it was like when we used film cameras and sent it for developing only to get them back a week later and half the photos were no good and blurry. Now with digital cameras we see it right away and take way more pictures than with film until it's perfect. We've become obsessed with only getting perfect pictures everytime. Well, newsflash, people are imperfect so no matter what they invent it will never be a perfect product as long as the makers are imperfect!!!
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Old Dec 23, 2004, 8:06 AM   #19
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True.....in the hands of somebody that knows what they're doing, they can get the optimum performance from a camera. Although the very low end cameras can be somewhat limited with fixed focus, poor lenses, imprecise mechanisms, and other things like that.
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Old Dec 23, 2004, 8:39 AM   #20
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Nickagain wrote:
Quote:
The A1 (5 mpxl CCD sensor) has no purple fringing, but the A2 which uses exactly the same lens, but has a different CCD (8 mpxl) does exhibit purple fringing under some conditions. Photos showing the A2's PF have been posted on another forum.

BTW, the A2 CCD is the same one that is used in the Sony 828. The 828 has severe purple fringing issues.
Actually, there is a difference with the CCD used in the Sony DSC-F828, compared to the Sony CCD used in the other 8MP Prosumer models.

The CCD used in the Sony has a different Color Filter Array. So, this could be a contributing factor (speculation on my part). It's also got a movable IR Cut (a.k.a., Hot Mirror) Filter.

I suspect that things like the Color Filter Array, Microlens size/design, and IR cut filters used on different sensors play a larger part than wesuspectwith this phenomena.
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